- From: Ian Jacobs <ij@w3.org>
- Date: Wed, 21 Mar 2001 17:54:07 -0500
- To: w3c-wai-ua@w3.org
Hello,
Please consider the following proposal, which I hope resolves a few
remaining conformance issues:
1) Is a given checkpoint for content only, for the user agent's
features only, or for both?
2) How should conformance work for pointing device and voice input?
3) Which checkpoints do I have to satisfy to conform?
Reference document: 19 March 2001 draft [0]
[0] http://www.w3.org/WAI/UA/WD-UAAG10-20010319/
==========
Proposal 1
Label checkpoints for content, user agent, or both.
==========
There are currently 87 checkpoints in the document. Some of them
apply to author-supplied content only, some to components of
the user agent only, and some to both. I am quite convinced of
the following:
a) Forty-five checkpoints apply to author-supplied content only:
Guidelines 2, 3, 4 (except 4.16), 5.4, 5.5, 6.1, 6.2, 6.3, 6.9,
Guideline 8, 10.1, 10.3, 10.4, 10.5, and 11.2.
b) Thirty-two checkpoints apply to components of the user agent only
(i.e., everything but the content):
1.2, 6.4, 6.7, Guideline 7, Guideline 9, 10.6-10.10, 11.1,
11.3-11.6, and Guideline 12.
c) Seven checkpoints apply to both:
1.1, 4.16, 6.5, 6.6, 6.8, 6.10, and 10.2.
Today, we have "informative" labels for identifying whether a
checkpoint is for content only, for the user agent only, or for both.
I think we need to make this clear in a normative fashion and propose
the following:
a) At the end of each checkpoint statement, next to the priority,
indicate (using some sort of label) whether the checkpoint is for
content only, for the user agent only, or for both.
b) Add a conformance section to which these labels would link
(and introduce the labels at the beginning of section 2 on
the structure of a checkpoint definition). The conformance
section might read something like this:
<NEW 3.x>
3.x Checkpoints for content, user agent features, or both
For some requirements of this document, "content" (the document
object) is distinguished from "user agent features" (everything
else besides the document object). User agent features include
functionalities provided by the user agent out of the box, native
user interface components, documentation, focus and selection, etc.
For conformance, a user agent is required to satisfy the
requirements of the checkpoint for content only, for user agent
features only, or for both.
</NEW 3.x>
c) Delete the various informative groupings:
* Checkpoints for content accessibility
* Checkpoints for user interface accessibility
* Checkpoints for communication with other software
* Checkpoints for accessible documentation
Note: Some of them are already misleading in the 19 March 2001
draft. For instance, checkpoint 1.1 is listed as being for
the user interface, but it also applies to content.
d) Add to the definition of DOM something like the following
statement:
"Most of the requirements of this document apply to content (i.e.,
the document object) after its construction. However, a few
checkpoints (e.g., 2.7, 2.8, and 2.10) may affect the construction
of the DOM."
e) Reformat the checklist so that checkpoints are no longer grouped
according to the labels of (c) but rather according to whether
for content, for ui, or for both.
==========
Proposal 2
Conformance for pointing device input and voice input
==========
I recently sent a proposal [1] for addressing some concerns about
conformance for pointing device input and voice input. I'd like
to amend that proposal slightly.
a) To conform, all input device requirements must be satisfied for
the keyboard.
b) To conform for pointing device input and voice input, the same
input device requirements must be satisfied for those input
devices, substituting "voice" or "pointing device" for "keyboard"
wherever it appears (namely in checkpoints 1.1, 6.7, 9.3, and 11.3).
However, there is one exception to this rule: checkpoint 11.3
refers to *single key access*. This requirement does not (I would
argue very strongly) translate to pointing device and voice input.
(I would argue this strongly because, while ease of access is
certainly a consideration, we developed this requirement very
specifically for single-physical-key access. I would not want
to try to generalize in this document to "single spoken gesture",
for example).
Because checkpoint 11.3 includes some requirements that are
specific to the keyboard and some that are not, I propose to split
the checkpoint in two (so that conformance will be easier to
understand). This would give:
11.3a Allow the user to override any binding that is part of the
user agent default input configuration. The user agent is not
required to allow the user to override standard bindings for the
operating environment (e.g., for access to help). [Priority 2]
11.3b Allow the user to override any binding in the default
keyboard configuration with a binding of a single key and
(possibly zero) modifier keys. Allow the user to assign a single
key binding (with zero modifier keys) to at least a majority of
the functionalities available in the default keyboard
configuration. [Priority 2]
c) Update the input modality label definitions as follows:
Pointer:
This input modality label refers to all of the input device
requirements of this document, applied to pointing device
input, except for checkpoint 11.3b. For all other
checkpoints, substitute "pointing device" for "keyboard"
in the checkpoints.
Voice:
This input modality label refers to all of the input device
requirements of this document, applied to voice input,
except for checkpoint 11.3b. For all other
checkpoints, substitute "voice input" for "keyboard"
in the checkpoints.
[1] http://lists.w3.org/Archives/Public/w3c-wai-ua/2001JanMar/0452
==========
Proposal 3
Some edits to section 3.1 Conformance model
==========
<NEW 3.1>
The conformance model of this document has been designed to allow
different types of user agents with different input and output
capabilities to conform. At the same time, this flexible model
includes requirements about conformance claims themselves so that:
a) people reading claims can determine whether a conforming user
agent is likely to meet their accessibility needs, and
b) people can compare claims about disparate user agents with
relative ease. Note: The checklist [UAAG10-CHECKLIST] may be
used when evaluating a user agent for conformance.
The conformance model works as follows:
- A user agent conforms to this document by satisfying a set of
requirements. Conformance requirements *only* come from the
checkpoint statements. Each checkpoint statement includes one or
more requirements.
- Different user agents may conform to different sets of
checkpoints. The formula below explains how to calculate a set
of requirements that must be satisfied for conformance.
- Conformance claims must indicate how the set of requirements
chosen for the claim differs from the "default" set. Please note
that this document includes both conformance requirements and
conformance claim requirements.
The "default" set of requirements for conformance consists of all
the requirements of all of the checkpoints. A user agent
"conforms unconditionally" to this document if it satisfies all
of the requirements of all of the checkpoints.
A user agent "conforms conditionally" if it satisfies any set of
requirements that results from carrying out all of the following
steps:
1) Choose a conformance level. Each conformance level
corresponds to a set of checkpoints (and thus a set of
requirements).
2) Remove the requirements associated with any unsupported
content type labels. In order to conform conditionally, a user
agent must satisfy the requirements of at least one content type
label.
3) Remove the requirements of any checkpoints or parts of
checkpoints that do not apply.
Note: In the default set of requirements, the only input device
requirements relate to keyboard input. It is also possible to
claim conformance for pointing device input and voice input; see
the section on input modality labels.
EXAMPLE
Consider a user agent with these capabilities:
* it supports keyboard and pointing device input;
* it renders text (in color) and several formats for
images, audio, and animations;
* it hands of video to a plug-in;
* it doesn't support speech output.
Step 1) Choose a conformance level. The claimant wishes to
conform at level Double-A. The resulting set of requirements
consists of all of the requirements of all the priority 1 and 2
checkpoints.
Step 2) Remove requirements related to content type labels.
The claimant wishes to claim conformance for the user
agent's support of text, images, audio, and video, but no other
animation formats. Since video is supported through a plug-in,
the plug-in must be in the conformance claim. The following
content type labels are therefore relevant: VisualText,
ColorText, Image, Animation, Video, and Audio. This means that:
* the claimant must remove the set of requirements associated
with the Speech content type label.
* the claimant must satisfy the requirements associated with
the other content type labels.
Step 3) Remove requirements that do not apply. Consider
checkpoint 4.4, for example, which is associated with both the
Audio and Animation content type labels:
4.4 Allow the user to slow the presentation rate of audio and
animations (including video and animated images). For a visual
track, provide at least one setting between 40% and 60% of the
original speed. For a prerecorded audio track including audio-only
presentations, provide at least one setting between 75% and 80% of
the original speed. When the user agent allows the user to slow the
visual track of a synchronized multimedia presentation to between
100% and 80% of its original speed, synchronize the visual and
audio tracks. Below 80%, the user agent is not required to render
the audio track. The user agent is not required to satisfy this
checkpoint for audio and animations whose recognized role is to
create a purely stylistic effect. [Priority 1]
Suppose that:
a) The claimant wishes to claim support for two audio formats;
b) The claimant wishes to claim support for one video format;
c) The claimant does not wish to claim support for two
animation formats (since the user agent doesn't
satisfy the requirements of 4.4 for those implemented formats);
d) The claimant does not wish to claim support for synchronized
multimedia (since the user agent doesn't
implement any synchronized multimedia formats).
The resulting requirements from this checkpoint would be:
a) For the audio formats:
Allow the user to slow the presentation rate of audio. For a
prerecorded audio track including audio-only presentations,
provide at least one setting between 75% and 80% of the original
speed.
b) For the video format:
Allow the user to slow the presentation rate of video. For a
visual track, provide at least one setting between 40% and 60% of
the original speed.
c) Limitation of scope for any format:
The user agent is not required to satisfy this checkpoint for
audio and animations whose recognized role is to create a purely
stylistic effect.
The following requirements do not apply:
a) When the user agent allows the user to slow the visual track of a
synchronized multimedia presentation to between 100% and 80% of its
original speed, synchronize the visual and audio tracks. Below 80%,
the user agent is not required to render the audio track.
The relevant applicability provision is provision three:
control of a content property that the subject cannot
recognize. In this case, no format implemented by the user
agent supports synchronized multimedia.
Step 4) Construct a well-formed conformance claim. For this
example (in addition to other required information), the claim must
include the following information:
a) Conformance level Double-A
b) Information about the subject, in this case the combination
of a multimedia user agent and a plug-in for rendering video.
c) Content type labels: "This user agent does not support
the requirements of the Speech content type label. This
user agent supports the requirements of the Animation
content type label for the format X, but does not for the
formats Y and Z."
d) Requirements that do not apply: "The synchronized multimedia
requirements of checkpoint 4.4 do not apply because the user
agent does not implement any formats that support
synchronized multimedia.
Note: Since the user agent does not meet the requirements of the
Pointer and Voice input modality labels, the claim does not
include them.
</NEW 3.1>
Comment:
a) I refer to "requirements" rather than "checkpoints" throughout
this section since a single checkpoint may include more than one
requirement. I need to make sure that section 3 uses the term
"requirement" rather than "checkpoint" in a uniform manner.
Your comments welcome,
- Ian
--
Ian Jacobs (jacobs@w3.org) http://www.w3.org/People/Jacobs
Tel: +1 831 457-2842
Cell: +1 917 450-8783
Received on Wednesday, 21 March 2001 17:54:10 UTC